[Federal Register Volume 66, Number 108 (Tuesday, June 5, 2001)]
[Proposed Rules]
[Pages 30114-30116]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-14042]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NM-146-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Supplemental notice of proposed rulemaking; reopening of 
comment period.

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SUMMARY: This document revises an earlier proposed airworthiness 
directive (AD), applicable to certain Boeing Model 737-100, -200, -300, 
-400, and -500 series airplanes, that would have required inspection of 
wire bundles in two junction boxes in the main wheel well to detect 
chafing or damage, and follow-on actions. This new action revises the 
proposed rule by expanding the applicability to include additional 
airplanes and models, and by adding new inspections for chafing or 
damage of two additional junction boxes in the main wheel well and 
follow-on actions for those boxes. This action is necessary to prevent 
wire damage, which could result in arcing and consequent fire in the 
main wheel well or passenger cabin, or inability to stop the flow of 
fuel to an engine or to the auxiliary power unit in the event of a 
fire. This action is intended to address the identified unsafe 
condition.

DATES: Comments must be received by July 10, 2001.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2000-NM-146-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056. Comments may be inspected at this 
location between 9:00 a.m. and 3:00 p.m., Monday through Friday, except 
Federal holidays. Comments may be submitted via fax to (425) 227-1232. 
Comments may also be sent via the Internet using the following address: 
[email protected]. Comments sent via fax or the Internet must 
contain ``Docket No. 2000-NM-146-AD'' in the subject line and need not 
be submitted in triplicate. Comments sent via the Internet as attached 
electronic files must be formatted in Microsoft Word 97 for Windows or 
ASCII text.
    The service information referenced in the proposed rule may be 
obtained from Boeing Commercial Airplane Group,

[[Page 30115]]

P.O. Box 3707, Seattle, Washington 98124-2207. This information may be 
examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, 
SW., Renton, Washington.

FOR FURTHER INFORMATION CONTACT: Stephen Oshiro, Aerospace Engineer, 
Systems and Equipment Branch, ANM-130S, FAA, Seattle Aircraft 
Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-
4056; telephone (425) 227-2793; fax (425) 227-1181.

SUPPLEMENTARY INFORMATION:

Comments Invited

    Interested persons are invited to participate in the making of the 
proposed rule by submitting such written data, views, or arguments as 
they may desire. Communications shall identify the Rules Docket number 
and be submitted in triplicate to the address specified above. All 
communications received on or before the closing date for comments, 
specified above, will be considered before taking action on the 
proposed rule. The proposals contained in this action may be changed in 
light of the comments received.
    Submit comments using the following format:
     Organize comments issue-by-issue. For example, discuss a 
request to change the compliance time and a request to change the 
service bulletin reference as two separate issues.
     For each issue, state what specific change to the proposed 
AD is being requested.
     Include justification (e.g., reasons or data) for each 
request.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the proposed rule. All 
comments submitted will be available, both before and after the closing 
date for comments, in the Rules Docket for examination by interested 
persons. A report summarizing each FAA-public contact concerned with 
the substance of this proposal will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this action must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 2000-NM-146-AD.'' The postcard will be date-stamped 
and returned to the commenter.

Availability of NPRMs

    Any person may obtain a copy of this NPRM by submitting a request 
to the FAA, Transport Airplane Directorate, ANM-114, Attention: Rules 
Docket No. 2000-NM-146-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    A proposal to amend part 39 of the Federal Aviation Regulations (14 
CFR part 39) to add an airworthiness directive (AD), applicable to 
certain Boeing Model 737-100, -200, -300, -400, and -500 series 
airplanes, was published as a notice of proposed rulemaking (NPRM) in 
the Federal Register on June 27, 2000 (65 FR 39574). That NPRM would 
have required inspection of wire bundles in two junction boxes in the 
main wheel well to detect chafing or damage, and follow-on actions. 
That NPRM was prompted by reports indicating that damaged electrical 
wiring has been found in a junction box formed by electrical disconnect 
brackets on the right side of the main wheel well on certain Boeing 
Model 737 series airplanes. That condition, if not corrected, could 
result in arcing and consequent fire in the main wheel well or 
passenger cabin, or inability to stop the flow of fuel to an engine or 
to the auxiliary power unit in the event of a fire.

Comments

    Due consideration has been given to the comments received in 
response to the NPRM. One comment has resulted in changes to the 
proposed rule, which are discussed below.

Expand Inspection Area, Applicability

    One commenter, the airplane manufacturer, requests that the FAA 
revise the NPRM in the following ways:
     Expand applicability to include all Boeing Model 737-100, 
-200, -300, -400, and -500 series airplanes; and Boeing Model 737-600, 
-700, -800, and -900 series airplanes, with line numbers 1 through 706 
inclusive.
     Expand subject area of inspections and follow-on actions 
to include two additional junction boxes in the main wheel well.
     Reference revised service information.
    The commenter explains that, though the NPRM specified inspections 
and follow-on actions for only two junction boxes in the main wheel 
well on certain Boeing Model 737 series airplanes, there are four 
junction boxes in the main wheel well area that have the same design. 
Also, junction boxes of the same design are installed on certain Boeing 
Model 737-600, -700, -800, and -900 series airplanes. The commenter 
requests that the FAA revise the NPRM to reference new service 
information that addresses these issues.
    The FAA concurs with the commenter's requests. Since the issuance 
of the proposed rule, the FAA has reviewed and approved Boeing Service 
Letter 737-SL-24-111-B, dated January 16, 2001. (The NPRM referenced 
Boeing Service Letter 737-SL-24-111, dated February 27, 1996, as the 
appropriate source of service information for the actions described in 
the NPRM.) Boeing Service Letter 737-SL-24-111-B differs from the 
original issue by featuring an expanded effectivity (including Model 
737-600, -700, -800, and -900) and an expanded inspection area (four 
junction boxes instead of two). The new service letter also 
incorporates new instructions for rerouting the wiring that are 
intended to better protect the wiring from future damage due to chafing 
than would the instructions in the original service letter. Also, the 
revised service letter refers only to Boeing Standard Wiring Practices 
Manual D6-54446, Subject 20-10-13, as an appropriate source of repair 
instructions if any damaged wiring is found. Accomplishment of the 
actions in the revised service letter described above is intended to 
adequately address the unsafe condition.

Conclusion

    Since these changes expand the scope of the originally proposed 
rule, the FAA has determined that it is necessary to reopen the comment 
period to provide additional opportunity for public comment.

Explanation of New Requirements of Supplemental NPRM

    Since an unsafe condition has been identified that is likely to 
exist or develop on other products of this same type design, the 
supplemental NPRM would require accomplishment of the actions specified 
in the revised service letter described previously, except as discussed 
below.

Difference Between Service Letter and This Proposed AD

    Operators should note that, while the service letter does not 
specify the type of inspection of the wire bundles to detect chafing, 
this proposed AD would require a detailed visual inspection to detect 
chafing of the wire bundles. A note has been included in this proposed 
rule to define that inspection.
    Operators also should note that this proposed AD would require the 
inspection be accomplished within 12 months after the effective date of 
the AD. The service letter specifies that the actions therein should be 
accomplished ``at a convenient opportunity when

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facilities and manpower are available.'' In developing an appropriate 
compliance time for this proposed AD, the FAA considered the degree of 
urgency associated with addressing the subject unsafe condition, the 
average utilization of the affected fleet, and the time necessary to 
perform the actions (approximately 4 hours). In light of all of these 
factors, the FAA finds a 12-month compliance time for initiating the 
required actions to be warranted, in that it represents an appropriate 
interval of time allowable for affected airplanes to continue to 
operate without compromising safety.

Cost Impact

    There are approximately 3,719 airplanes of the affected design in 
the worldwide fleet. The FAA estimates that 1,467 airplanes of U.S. 
registry would be affected by this proposed AD, that it would take 
approximately 8 work hours per airplane to accomplish the proposed 
actions, and that the average labor rate is $60 per work hour. The cost 
of required parts would be negligible. Based on these figures, the cost 
impact of the proposed AD on U.S. operators is estimated to be 
$704,160, or $480 per airplane.
    The cost impact figure discussed above is based on assumptions that 
no operator has yet accomplished any of the proposed requirements of 
this AD action, and that no operator would accomplish those actions in 
the future if this proposed AD were not adopted. The cost impact 
figures discussed in AD rulemaking actions represent only the time 
necessary to perform the specific actions actually required by the AD. 
These figures typically do not include incidental costs, such as the 
time required to gain access and close up, planning time, or time 
necessitated by other administrative actions.

Regulatory Impact

    The regulations proposed herein would not have a substantial direct 
effect on the States, on the relationship between the national 
Government and the States, or on the distribution of power and 
responsibilities among the various levels of government. Therefore, it 
is determined that this proposal would not have federalism implications 
under Executive Order 13132.
    For the reasons discussed above, I certify that this proposed 
regulation (1) is not a ``significant regulatory action'' under 
Executive Order 12866; (2) is not a ``significant rule'' under the DOT 
Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); 
and (3) if promulgated, will not have a significant economic impact, 
positive or negative, on a substantial number of small entities under 
the criteria of the Regulatory Flexibility Act. A copy of the draft 
regulatory evaluation prepared for this action is contained in the 
Rules Docket. A copy of it may be obtained by contacting the Rules 
Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration proposes to amend 
part 39 of the Federal Aviation Regulations (14 CFR part 39) as 
follows:

PART 39--AIRWORTHINESS DIRECTIVES

    1. The authority citation for part 39 continues to read as follows:

    Authority: 49 U.S.C. 106(g), 40113, 44701.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

Boeing: Docket 2000-NM-146-AD.

    Applicability: All Model 737-100, -200, -300, -400, and -500 
series airplanes; and Model 737-600, -700, -800, and -900 series 
airplanes, line numbers 1 through 706 inclusive; certificated in any 
category.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
modified, altered, or repaired in the area subject to the 
requirements of this AD. For airplanes that have been modified, 
altered, or repaired so that the performance of the requirements of 
this AD is affected, the owner/operator must request approval for an 
alternative method of compliance in accordance with paragraph (b) of 
this AD. The request should include an assessment of the effect of 
the modification, alteration, or repair on the unsafe condition 
addressed by this AD; and, if the unsafe condition has not been 
eliminated, the request should include specific proposed actions to 
address it.

    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent chafing of wire bundles in four junction boxes in the 
main wheel well, which could result in arcing and consequent fire in 
the main wheel well or passenger cabin, or inability to stop the 
flow of fuel to an engine or to the auxiliary power unit in the 
event of fire, accomplish the following:

Inspection

    (a) Within 12 months after the effective date of this AD, 
perform a detailed visual inspection of the wire bundles in the four 
junction boxes formed by electrical disconnect brackets on the left 
and right sides of the main wheel wells to detect damage or chafing, 
as specified in Boeing Service Letter 737-SL-24-111-B, dated January 
16, 2001.

    Note 2: For the purposes of this AD, a detailed visual 
inspection is defined as: ``An intensive visual examination of a 
specific structural area, system, installation, or assembly to 
detect damage, failure, or irregularity. Available lighting is 
normally supplemented with a direct source of good lighting at 
intensity deemed appropriate by the inspector. Inspection aids such 
as mirror, magnifying lenses, etc., may be used. Surface cleaning 
and elaborate access procedures may be required.''

    (1) If no chafing is detected, prior to further flight, protect 
the wire bundles from chafing against the cover plate of the 
junction box, according to the service letter.
    (2) If any chafing is detected, prior to further flight, repair 
the wiring in accordance with the service letter, and protect the 
wire bundles from chafing against the cover plate of the junction 
box, according to the service letter.

    Note 3: Boeing Service Letter 737-SL-24-111-B, dated January 16, 
2001, refers to Boeing Standard Wiring Practices Manual D6-54446, 
Subject 20-10-13, as the appropriate source of repair instructions 
if any damaged wiring is found.

Alternative Methods of Compliance

    (b) An alternative method of compliance or adjustment of the 
compliance time that provides an acceptable level of safety may be 
used if approved by the Manager, Seattle Aircraft Certification 
Office (ACO), FAA. Operators shall submit their requests through an 
appropriate FAA Principal Maintenance Inspector, who may add 
comments and then send it to the Manager, Seattle ACO.

    Note 4: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.

Special Flight Permits

    (c) Special flight permits may be issued in accordance with 
Secs. 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 
21.197 and 21.199) to operate the airplane to a location where the 
requirements of this AD can be accomplished.

    Issued in Renton, Washington, on May 30, 2001.
Vi L. Lipski,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 01-14042 Filed 6-4-01; 8:45 am]
BILLING CODE 4910-13-P